1. Field of the Invention
The invention relates to an internal combustion engine control apparatus and method that can selectively increase and decrease the flow strength of fuel and air and the like in a cylinder of an internal combustion engine mounted in a vehicle for example.
2. Description of the Related Art
One known internal combustion engine control apparatus controls the intake and exhaust of an internal combustion engine by changing the valve timing using a so-called variable valve timing (VVT) mechanism.
For example, Japanese Patent Application Publication No. 2005-171871 (JP-A-2005-171871) describes technology that prevents residual gas in a cylinder from increasing by changing the valve timing of an intake valve of an internal combustion engine when a vehicle is decelerating.
Moreover, this kind of technology that changes the valve timing is used to prevent the combustion state from deteriorating when returning from a fuel cut in an internal combustion engine with a fuel cut function.
For example, Japanese Patent Application Publication No. 2006-144685 (JP-A-2006-144685) describes technology that reduces the amount of residual gas by decreasing the amount of recirculated exhaust gas by changing the valve timing when returning from a fuel cut.
Also, Japanese Patent Application Publication No. 2002-89302 (JP-A-2002-89302) describes technology that increases the actual compression ratio by changing the valve timing when returning from a fuel cut.
However, because the residual gas, air, and fuel and the like is not sufficiently mixed in the cylinder, for example, by only reducing the amount of residual gas and increasing the actual compression ratio when returning from a fuel cut, as is done in the technologies described above, misfiring or the like may result. That is, with the foregoing technologies, it is difficult to sufficiently improve a deteriorated combustion state in an internal combustion engine.